Sime watched him covertly, and saw that his face had acquired lines--lines which told of the fires through which he had passed. Something, it was evident--something horrible--had seared his mind. Considering the many indications of tremendous nervous disaster in Cairn, Sime wondered how near his companion had come to insanity, and concluded that he had stood upon the frontiers of that grim land of phantoms, and had only been plucked back in the eleventh hour. Cairn glanced around with a smile, from the group of hawkers who solicited his attention upon the pavement below. "This is a delightful scene," he said. "I could sit here for hours; but considering that it's some time after sunset it remains unusually hot, doesn't it?" "Rather!" replied Sime. "They are expecting _Khamsin_--the hot wind, you know. I was up the river a week ago and we struck it badly in Assouan. It grew as black as night and one couldn't breathe for sand. It's probably working down to Cairo." "From your description I am not anxious to make the acquaintance of _Khamsin_!" Sime shook his head, knocking out his pipe into the ash-tray. "This is a funny country," he said reflectively. "The most weird ideas prevail here to this day--ideas which properly belong to the Middle Ages. For instance"--he began to recharge the hot bowl--"it is not really time for _Khamsin_, consequently the natives feel called upon to hunt up some explanation of its unexpected appearance. Their ideas on the subject are interesting, if idiotic. One of our Arabs (we are excavating in the Fayum, you know), solemnly assured me yesterday that the hot wind had been caused by an Efreet, a sort of Arabian Nights' demon, who has arrived in Egypt!" He laughed gruffly, but Cairn was staring at him with a curious expression. Sime continued: "When I got to Cairo this evening I found news of the Efreet had preceded me. Honestly, Cairn, it is all over the town--the native town, I mean. All the shopkeepers in the Muski are talking about it. If a puff of _Khamsin_ should come, I believe they would permanently shut up shop and hide in their cellars--if they have any! I am rather hazy on modern Egyptian architecture." Cairn nodded his head absently. "You laugh," he said, "but the active force of a superstition--what we call a superstition--is sometimes a terrible thing." Sime stared. "Eh!" The medical man had suddenly come uppermost; he recollected that this class of discussion was probably taboo. "You may doubt the existence of Efreets," continued Cairn, "but neither you nor I can doubt the creative power of thought. If a trained hypnotist, by sheer concentration, can persuade his subject that the latter sits upon the brink of a river fishing when actually he sits upon a platform in a lecture-room, what result should you expect from a concentration of thousands of native minds upon the idea that an Efreet is visiting Egypt?" Sime stared in a dull way peculiar to him.